军队从来都是一个自成一体的社会。
南宾夕法尼亚仍是一个自成一体的世界。
得承认这只是一种理论,但其各部分自成一体。
It's only a theory, admittedly, but the pieces fit together.
Both of them are self-contained courses, so you could take either 251 or 252, or you could take both.
两门课都自成一体,你可以在251号和252号中任选一个,或者都选也行
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